Detection of circulating tumor cells in patients with prostate cancer using prostate specific membrane-derived primers in the polymerase chain reaction.

BACKGROUND

Prostate specific membrane antigen (PSM) is a transmembrane glycoprotein that has been described as human prostate specific. It is possible that PSM could be used as a biomarker for staging prostate cancer.

METHODS

Peripheral blood mononuclear cells from 2 groups of patients with prostate cancer were used for the detection of PSM messenger ribonucleic acid (mRNA) using the reverse transcriptase-polymerase chain reaction (RT PCR) method. Group 1 consisted of 29 untreated patients (13 stage B cancer, 5 stage C, and 11 stage D cancers). Group 2 consisted of 40 treated patients (23 responded well and 17 had recurrence after treatment). In addition, blood specimens from 30 patients with benign prostatic hyperplasia, 5 women, and 5 men undergoing cystoprostatectomy for invasive bladder cancer were used as controls. We then correlated patient and disease characteristics with PCR assay results.

RESULTS

Samples of all 40 controls were negative for PSM-mRNA. Thirteen of 29 patients of group 1 (45%) were positive for PSM-mRNA. The PCR positive rate did not correlate with clinical stage, pathologic stage, tumor grade, or serum PSA levels. Nine of 40 patients (22%) in group 2 were positive for PSM-mRNA, and the majority (8 of 9) were derived from the group of patients with recurrent disease.

CONCLUSIONS

A nested RT PCR assay for PSM mRNA can detect circulating tumor cells in the peripheral blood of patients with prostatic cancer. These results suggest that the detection of circulating tumor cells could be useful for monitoring disease progression of prostatic cancer.